Fuel injection nozzle holder seal

ABSTRACT

A fuel injection nozzle holder assembly and a differential valve pressure adjusting screw for accurately maintaining the differential valve opening pressure and lift.

14 1 Oct. 23, 1973 United States Patent 11 1 Dreisin [54] FUEL INJECTION NOZZLE HOLDER SEAL 3,093,310 6/1963 Wagner........................... 239/533 X v 1964 R Alexander Dreisin, Olympia Fields, 9/ 3 [75] Inventor:

FOREIGN PATENTS OR APPLICATIONS Assignee: Allis-Chalmers Corporation,

1,215,584 12/1970 Great Britain...................... 239/533 Milwaukee, Wis.

Feb. 25, 1972 22 Filed:

Primary ExaminerM. Henson Wood, .lr. Assistant Examiner-Andres Kashnikow Attorney-Arthur L. Nelson et a1.

21 Appl. No.: 229,455

ABSTRACT A fuel injection nozzle holder assembly and a differential valve pressure adjusting screw for accurately maintaining the differential valve opening pressure and lift.

[56] References Cited UNITED STATES PATENTS 3,511,443 5 1970 Gukin et 239/533 i 10 Claims, 4 Drawing Figures FUEL INJECTION NOZZLE HOLDER SEAL This invention relates to a fuel injection nozzle and more particularly to a holder for a fuel injection nozzle and differential valve pressure adjusting screw with sealing and locking means for maintaining a constant opening pressure and differential valve lift.

The conventional fuel injection nozzle assembly includes a nozzle holder connected to a nozzle containing the differential valve. The nozzle holder is threaded on its internal periphery and threadedly receives an adjusting screw. A lock nut and a nozzle holder cap also threadedly engage the external periphery of the adjusted screw. The conventional construction includes a seal on the external periphery of the adjusting screw and spaced between the nozzle holder and the lock nut, as well as between the locknut and the nozzle cap to seal the low pressure side of the nozzle assembly. Ordinarily the adjusting screw can be adjusted to vary the force of the spring biasing the spindle against the differential valve to control the opening pressure of the differential valve.

The low pressure or drain side of the nozzle assembly transmits fluid around the spindle and through the spring chamber to a drain passage. The spring exerts a considerable downward force counteracting the hydraulic pressure on the nozzle needle. This force can be on the order of eighty pounds or more. The exact amount of the force is regulated by means of a pressure adjusting screw which is threaded in and out of the holder assembly in order to achieve the same nominal nozzle. opening pressure for all assemblies of the given model.

Due to the high contact pressures developed between the external threads of the pressure adjusting screw and the internal threads on the nozzle holder body, very small chips, burrs, or shavings are frequently generated in assembling and during the process of final pressure adjusting screw setting.

In the normal operation of these assemblies, the space surrounding the spindle and spring is filled with low pressure fuel which has leaked by the nozzle needle and flows through the nozzle holder cap and appropriate tubing back to the fuel tank. The fuel usually flushes the small metal particles generated by the screw adjustment away from the walls and the force of gravity causes them to settle in the lowest point of the nozzle interior. In the majority of engine installations, the nozzle is directed downward and consequently the metal particles finally settle on the top of the needle shoulder.

In operation the nozzle needle lift is limited by the clearance between the'needle shoulder and the lower face of the holder body'against which it abuts. The needle lift can be typically as small as 0.01 of an inch and a small chip of, for example, 0.005 of an inch thickness can cut the effective nozzle lift by half, causing undue restriction during the injection of fuel and resulting in a lower power output from the corresponding engine cylinder, usually accompanied by increased smoke;

Accordingly, this invention proposes to eliminate a possibility of metal chips interfering with the nozzle lift. A sealing ring has been placed below the threads of the pressure adjusting screw. The pressure adjusting screw has an extended portion below the threads with a smooth outside diameter which cooperates with the seal ring.

Accordingly, any particles generated during the pressure adjustment process between the threads are trapped above the sealing ring, and cannot work their way downwardly towards the nozzle needle. This ar rangement, in addition, eliminates the need for sealing gaskets on the nozzle holder cap and nut which is used in the conventional nozzle assembly.

It is an object of this invention to provide a nozzle holder assembly and a differential valve adjusting screw for maintaining a constant opening pressure and effective differential valve lift.

It is another object of this invention to provide a nozzle holder seal between the threaded portion of the adjusted screw and the interior drain passage of the fuel injection nozzle.

It is a further object of this invention to provide a nozzle holder seal on the inside of the holder assembly to prevent foreign material from interfering with proper operation of the differential valve.

It is a further object of this invention to provide a seal between the threaded adjusting portion of the differential valve adjusting screw and the differential valve of the nozzle assembly.

The objects of this invention are accomplished by providing a nozzle holder with a differential valve in a nozzle assembly connected to the lower end of the nozzle holder and forming a bore extending centrally through the holder forreceiving a spindle. An enlarged spring chamber is formed by the adjusting screw which is threadedly received in an enlarged counterbored portion of the nozzle holder. A lock nut similarly threadedly engages the external periphery of the adjusting screw and locks against the upper surface of the nozzle holder to lock the nozzle assembly and retain the spring length and force at the desired differential valve opening pressure. A smooth cylindrical portion of the nozzle holder and the adjusting screw immediately below the threaded portion engage a seal to seal the spring chamber from the outside of the nozzle holder. The seal prevents foreign material from the threaded portion of adjusting screw from entering the return passages which return fuel from the nozzle assembly. This permits maintaining a constant differential valve lift and closing pressure.

Referring to the drawings, FIG. 1 illustrates a cross section view of the fuel injection nozzle.

FIG. 2 illustrates a side view of the fuel injection nozzle shown in FIG. 1.

FIG. 3 is an enlarged cross section view of the adjusting screw, the nozzle holder, and the differential valve closing spring assemblies.

FIG. 4 is an enlarged cross section view of the lower portion of the nozzle assembly including the differential valve.

Referring to the drawings, FIG. 1 and FIG. 2 illustrate two views of the fuel injection nozzle assembly. The nozzle holder 1 is formed with an inlet passage 2 adapted for connection to the fuel supply. The drain passage 3 is adapted for connection to a drain conduit to return fuel to the fuel tank. Low pressure fuel is sup plied through the inlet passage 2 and 4 to the differential valve chamber 5. The differential valve 6 controls the discharge of fluid through the orifices 7 of the nozzle tip. The differential valve 6 opens to permit discharge of high pressure fuel when the pressure in the chamber 5 reaches a predetermined value. The nozzle assembly 8 is fastened to the lower portion of the nozzle holder 1 by a nozzle retaining nut 9 and is aligned by the dowel pin 10.

The nozzle holder 1 is formed with a central bore 11 which receives the spindle 12 which seats on the upper end of the differential valve needle 13. The spindle 12 forms a spring seat 14 which seats the spring 15. A washer 16 engages the upper end of the spring 15 of the adjusting screw 17. The adjusting screw 17 is threaded on its external periphery and threadedly engages the threaded portion 18 of the nozzle holder in the enlarged opening 19 of its upper end.

The enlarged opening 19 of the nozzle holder also has a cylindrical lower surface 20. The annular groove 21 receives the seal 22. The screw 17 also has a lower cylindrical surface 23 which engages the seal 21 to seal the drain passage 3 and spring chamber 24.

The adjusting screw 17 is threaded on its external periphery and threadedly engages the threaded portion of the nozzle holder to provide adjustment of the length of spring 15 for controlling the opening pressure of the differential valve 6. The lock nut 25 also threadedly engages adjusting screw l7 and locks the screw 17 with the holder 1 to set the opening pressure of the differential valve at a predetermined value.

Low pressure fuel is supplied through the inlet passage 2 which in turn is supplied to the chamber in the differential valve 6. During the phase of the cycle of fuel injection the pressure in the chamber 5 drastically increases causing the differential valve needle 13 to lift permitting the discharge of high pressure fuel through the orifices 7 of the nozzle assembly 8. Fuel injection continues only for the period at which the pressure in the chamber 5 is sufficient to overcome the force of the spring biasing the differential valve needle 13 toward a closed position. The spring 15 is compressively positioned between the washer 16 in the adjusting screw 17 and the spindle 12 to produce a heavy force on the spindle to bias the differential valve 6 to a closed position when there is no fuel injection.

The adjusting screw 17 extends downwardly into the chamber 24 and can be adjustably screwed upwardly or downwardly by the hexagon head 26. When the differential valve is calibrated to the predetermined closing pressure by adjusting the screw 17, the lock nut 25 is tightened against the upper surface 27 of the holder 1. The opening of the differential valve is limited by the shoulder 28 of the differential valve needle 13 which abuts against the abutting surface 29 of the nozzle holder. The clearance between the shoulder 28 and the surface 29 is in the order of 0.010 of an inch. Accordingly, it is necessary that foreign material such as shavings, burrs, and so on, are prevented from falling into i in the drain passage 3 or spring chamber 24 and depositing into the lower portion of the bore 11. Accordingly, the seal 22 below the threaded portions of the screw 17 and the nozzle holder I prevent chips, burrs and shavings generated by the screw threads from falling into the bore 11 and depositing on the differential valve shoulder 28. This in turn permits the adjusting screw 17 to be effective in adjusting the nozzle closing pressure and permitting the differential valve to fully open to a preset constant distance.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A fuel injection nozzle holder assembly comprising a nozzle holder defining a central bore having a threaded internal portion on its upper end, a nozzle including a differential valve connected to the lower end of said nozzle holder with said differential valve connected with said bore, a differential valve opening pressure adjusting screw having a cylindrical lower portion and a threaded upper portion threadedly engaging the threaded portion of said holder, a differential valve needle in said differential valve, a spindle and differential valve closing spring compressively positioned between said adjusting screw and said differential valve needle, a valve movement limiting means limiting the opening movement of said differential valve including a shoulder defined by said differential valve needle, an abutting surface on said nozzle holder for engaging said shoulder when said valve is open, a seal positioned between the threaded portion of said adjusting screw and said valve movement limiting means, said seal engaging the bore of said holder and the cylindrical surface of said adjusting screw and providing a fluid tight seal preventing particles loosened from the threaded portion of said nozzle holder when said differential valve is adjusted from entering said fuel injection nozzle holder assembly.

2. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle holder assembly includes, a lock nut to adjustably lock said adjusting screw to maintain a predetermined opening pressure of said differential valve.

3. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said bore in said nozzle holder defines a drain passage, means defining a supply passage connected to said differential valve for supplying fuel for fuel injection.

4. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said bore in said nozzle holder includes means defining an enlarged opening in the upper end of said bore, said adjusting screw and said enlarged opening in said nozzle holder defining a spring chamber for receiving said differential valve closing spring.

5. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle defines a differential valve chamber, said differential valve needle includes means extending into said chamber adapted for opening in response to pressurized fluid of a predetermined value in said differential valve chamber, said bore in said nozzle holder defining a drain passage adapted for draining fuel leakage from said differential valve to a fuel tank.

6. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle holder defines an enlarged opening at the upper end of said bore, said adjusting screw and said nozzle holder define a spring chamber for receiving said differential valve closing spring, means defining an annular groove in said nozzle holder, a seal received in said groove for slidably engaging the cylindrical portion of said adjusting screw.

7. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said adjusting screw defines a reduced diameter cylindrical lower portion, an annular groove in said bore of said nozzle holder adapted for receiving said seal and slidably engaging the cylindrical surface of said adjusting screw.

8. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said spindle defines a spring scat, means defining a spring opening in said adjusting screw, said differential valve closing spring compressively positioned between said adjusting screw and said forth in claim 1 wherein said nozzle holder defines a radial surface on its upper end, said adjusting screw defines a threaded external periphery on its upper portion, a locking nut threadedly received on the external periphery of said adjusting screw to thereby lock said adjusting screw in said nozzle holder when said lock nut is tightened against said radial surface of said nozzle holder to thereby maintain a constant force for main taining the opening pressure of said differential valve. 

1. A fuel injection nozzle holder assembly comprising a nozzle holder defining a central bore having a threaded internal portion on its upper end, a nozzle including a differential valve connected to the lower end of said nozzle holder with said differential valve connected with said bore, a differential valve opening pressure adjusting screw having a cylindrical lower portion and a threaded upper portion threadedly engaging the threaded portion of said holder, a differential valve needle in said differential valve, a spindle and differential valve closing spring compressively positioned between said adjusting screw and said differential valve needle, a valve movement limiting means limiting the opening movement of said differential valve including a shoulder defined by said differential valve needle, an abutting surface on said nozzle holder for engaging said shoulder when said valve is open, a seal positioned between the threaded portion of said adjusting screw and said valve movement limiting means, said seal engaging the bore of said holder and the cylindrical surface of said adjusting screw and providing a fluid tight seal preventing particles loosened From the threaded portion of said nozzle holder when said differential valve is adjusted from entering said fuel injection nozzle holder assembly.
 2. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle holder assembly includes, a lock nut to adjustably lock said adjusting screw to maintain a predetermined opening pressure of said differential valve.
 3. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said bore in said nozzle holder defines a drain passage, means defining a supply passage connected to said differential valve for supplying fuel for fuel injection.
 4. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said bore in said nozzle holder includes means defining an enlarged opening in the upper end of said bore, said adjusting screw and said enlarged opening in said nozzle holder defining a spring chamber for receiving said differential valve closing spring.
 5. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle defines a differential valve chamber, said differential valve needle includes means extending into said chamber adapted for opening in response to pressurized fluid of a predetermined value in said differential valve chamber, said bore in said nozzle holder defining a drain passage adapted for draining fuel leakage from said differential valve to a fuel tank.
 6. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle holder defines an enlarged opening at the upper end of said bore, said adjusting screw and said nozzle holder define a spring chamber for receiving said differential valve closing spring, means defining an annular groove in said nozzle holder, a seal received in said groove for slidably engaging the cylindrical portion of said adjusting screw.
 7. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said adjusting screw defines a reduced diameter cylindrical lower portion, an annular groove in said bore of said nozzle holder adapted for receiving said seal and slidably engaging the cylindrical surface of said adjusting screw.
 8. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said spindle defines a spring seat, means defining a spring opening in said adjusting screw, said differential valve closing spring compressively positioned between said adjusting screw and said spring seat to compressively bias said differential valve towards a closed position.
 9. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said adjusting screw defines a cylindrical opening for receiving said differential valve closing spring, said nozzle holder defines an enlarged cylindrical opening in communication with said bore to thereby define a spring chamber for compressively positioning said differential valve closing spring in said nozzle assembly.
 10. A fuel injection nozzle holder assembly as set forth in claim 1 wherein said nozzle holder defines a radial surface on its upper end, said adjusting screw defines a threaded external periphery on its upper portion, a locking nut threadedly received on the external periphery of said adjusting screw to thereby lock said adjusting screw in said nozzle holder when said lock nut is tightened against said radial surface of said nozzle holder to thereby maintain a constant force for maintaining the opening pressure of said differential valve. 